Artist concept of the James Webb Space Telescope. Credit: NASA/Northrop Grumman

It wasn't easy to choose the top stories for 2021. Although it was another hard year for people around the world, the year was also full of interesting astronomy and space events. Here are my choices.

JWST – at last! Christmas day saw the launch of NASA's James Webb Space Telescope – a project over three decades in the making. An infrared telescope must keep cool, so it headed off to a gravitationally stable Lagrange Point, L2. It will stay in line with Earth, the telescope pointing away from the Earth and its sunshield blocking sunlight. "JWST's primary aim is to shed light on our cosmic origins. It will observe the Universe's first galaxies, reveal the birth of stars and planets, and look for exoplanets with the potential for life."

February visitors to Mars. The United Arab Emirates’s Hope orbiter was first to arrive, but followed into orbit the next day by China's Tianwen-1. NASA's Perseverance rover was the last arrival. It landed safely, and a few months later was at work collecting samples, some of which are to be returned to Earth. In May Tianwen released a lander and rover, making China the third country to land a rover on Mars.

Ingenuity. Perseverance didn't go alone to Mars. The robotic aircraft Ingenuity went with it. By early December, Ingenuity had not only made the first ever flight of a robotic aircraft on another world, but had also made 16 further test flights.

Comet Bernardinelli-Bernstein. This isn't any old comet, it's the biggest comet ever known. It was discovered by researchers searching Dark Energy Survey data for objects beyond Neptune's orbit. This currently very distant object was named for the two researchers. Within a decade astronomers will get a better view of the comet, as it will be visiting the Solar System. (NOTE: It won't be coming close to Earth.)

How moons form in young star systems. There are theories, but evidence is lacking. One research group found a hint of a "moon-forming" disc around exoplanet PDS 70c, but it wasn't clear enough to confirm a detection. The first good evidence showed up last year for a team that used the ALMA array in Chile to focus on PDS 70c. They found a debris disc around the planet with such good resolution that they could "clearly identify that the disc is associated with the planet and . . . to constrain its size for the first time."

EHT is back. Remember the astounding first photo of a black hole in 2019? It was taken by the Event Horizon Telescope, a collaboration of observatories that work together to make one Earth-sized telescope. In July 2021, the EHT published a high resolution image of a powerful jet ejected by the supermassive black hole of Centaurus A.

The Sun is waking up. Our Sun has been fairly quiet in the last decade, but it's getting active again. For example, in early November Earth received some stellar outbursts known as coronal mass ejections (CMEs). If this stream of energetic particles flung out into the Solar System hits Earth, it interacts with our magnetic field. The nice bit is beautiful aurorae. The downside is that there can be damage to power plants, pipelines, satellites and GPS.

The solar wind. A CME is a violent and uncommon event, but the Sun also continuously sends out a stream of charged particles known as the solar wind. Since this affects Earth, scientists are interested in finding out what creates it and at what point the particles flow out from the Sun and do not return. The area in which this happens is called the pseudostreamer. From Earth it's only visible during total solar eclipses when the Moon blocks sunlight. Until recently it was impossible to get close enough to the Sun to work out exactly where this area is. Last year NASA's Parker Solar Probe went into the corona – the Sun's outer atmosphere – and passed through the pseudostreamer. It supplied data that provided the precise location of the point of no return.

NASA launched two asteroid-hunting missions. (1) A fossilized ancient human that advanced our knowledge of human history was nicknamed "Lucy". The mission to study Jupiter's Trojan asteroids also got the name Lucy. That's because the Trojans are objects left over from ancient planet formation, and Lucy will study them for clues to the Solar System’s evolution. (2) The other mission is the Double Asteroid Redirection Test (DART). It's headed for a binary asteroid system where it will smack into its moon Dimorphos, in an attempt to move it slightly out of orbit. If successful, this technology could help NASA and other space agencies protect the Earth from asteroid impacts.

The Winchcombe meteorite. Japan has returned samples from asteroids, and the USA has some on the way home. But in February the UK received a sample that brought itself to Earth. A fireball got considerable attention as it streaked across the country, finally hitting the ground on a driveway in Winchcombe, Gloucestershire and scattering pieces around. A public appeal enabled scientists to recover what turned out to be significant pieces of an uncontaminated primitive meteorite containing materials essentially unaltered since the formation of the Solar System.